An important point to mention here is that the two EJB servers should be
same - I am not aware of transaction contexts being interoperable between
different app servers at the moment
please correct me if my understanding is wrong
-cheers
Saurabh
----- Original Message -----
From: "Jonathan K. Weedon" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, November 10, 2000 5:18 AM
Subject: Re: Two Phase commit
> Richard,
>
> Sorry, but you are wrong.
>
> It is possible to have two servers access a single database
> in a single transaction. Two phase commit is not required for
> this (as there is only a single resource), although XA is
> required (so that the TM can determine that the two resources
> are in fact the same, in that they have the same XA id).
>
> IAS 4.1.x provides such support out-of-the-box. That is, you
> can have any number of EJBs access the same database from any
> number of containers, all in a single transaction, and not
> need 2PC.
>
> Many people don't realize this is possible because almost every
> TM on the market does not support this optimization. For example,
> neither Tuxedo nor Encina can pull off this trick.
>
> Of course, if you actually have two resources (that is, an Oracle
> and a Sybase) both enlisted in the same transaction, then you
> will need 2PC. And of course our product provides this capaibility
> too, although it is more expensive due to the logging overhead
> required to make the 2PC recoverable.
>
> -jkw
>
> Richard Monson-Haefel wrote:
> >
> > Although you are access the same database (resource) you will still need
application servers that support two-phase commit (2PC) in order to execute
operations
> > across servers within a single transaction. The this is required
because you are using two separate connections to the database that would
otherwise be unaware of
> > each other. You need to 2PC to inform the database that these two
database connections are working together within the same transaction.
> >
> > It's feasible that a vendor could provide connection sharing through
some type of database gateway -- that would eliminate the need for 2PC --
but I'm not aware of
> > one that does this.
> >
> > Richard
> > --
> > Richard Monson-Haefel
> > Author of Enterprise JavaBeans, 2nd Edition (O'Reilly 2000)
> > Co-Author of Java Message Service (O'Reilly 2000)
> > http://www.EjbNow.com
> >
> > "Maliyackel, Anup Kumar (CTS)" wrote:
> >
> > > hi
> > >
> > > I have read that when developinng J2ee applications using two app
servers or
> > > two databases, the two phase commit protocol is necessary to maintain
data
> > > consistency.
> > >
> > > If I am using two app servers , but writing to the same database how
> > > important is this?
> > >
> > > Regards
> > > Anup
> > >
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